Hydrotherapy involves circulating heated water around the body, optimally while air agitating the water for added massaging action. The use of cool, ambient air, however, cools the heated water and reduces the hydrotherapy benefits. In smaller installations such as in the home, a separate heater may not be provided for the water beyond the heat afforded by the household hot water heater, and therapy tubs in such circumstances are difficult to keep at adequate temperatures. The use of continuously running fresh hot water to maintain heat in the therapy tub is wasteful of energy and unduly expensive.